Substance P is not involved in vascular nociception in humans.

Blood vessels are similar to skin invested with substance P-containing nerves and the binding sites for substance P, which has been shown to be involved in nociception from skin. No attempts have been made so far to see whether substance P is also involved in vascular nociception. We therefore tested substance P for its algesic properties in human veins because their innervation exclusively subserves nociception. Substance P never evoked pain from veins at concentrations of 10(-8)-10(-4) M but did so in a concentration-related fashion from skin. Therefore, substance P is not involved in the generation of acute vascular pain.